Vegetarian Journal

Excerpts

Jul/Aug 1997

Volume XVI, Number 4

Acquaculture: An Overview

Part II, By Jeanne-Marie Bartas

Summary of Part I

In Part I of this two-part
article (Vegetarian Journal, May/June 1997 issue),
we looked at several aspects of aquaculture, including the industry's management
of its source and quality of water and feeds, and scientific research in
aquaculture. In this part, we will examine regulatory issues and the environmental
impacts of aquaculture. We will then briefly suggest what the future of
aquaculture will be and close with the author's analysis and commentary.

Regulation of Aquaculture

Aquaculture is regulated on both the state and federal levels. All aspects
of fish farming, including fish rearing, harvesting (of wild-caught fish),
medication, processing, and selling are regulated, although certain aspects
are more regulated than others. The regulatory agencies include the Food
and Drug Administration (FDA), the Environmental Protection Agency (EPA),
the Department of Agriculture, and the Department of Health and Human Services.
In the interest of space, we will restrict our discussion to the regulation
of therapeutants (commonly known as drugs), and the regulation of the effluent
(liquid waste water) and solid waste produced by the industry.

The topic of drug regulation should be of great concern to those who consume
fish, because the health risks associated with drug residues in seafood
are largely unknown. The concern is heightened by the fact that most of
the seafood eaten by Americans is from foreign sources. Since the regulation
of seafood safety and the number of permitted drugs in aquaculture varies
from country to country, the consumer of seafood may be taking a risk of
which he or she may not even be aware.

The topic of effluent and solid waste regulation in aquaculture is of interest
to everyone, in that these wastes impact our common environment, especially
our water and land. As regard for the environment is becoming more and
more important to many people, it will be informative to look at how our
government regulates aquaculture's waste products.

Drugs

There are five FDA-approved drugs for use in food fish in the U.S., compared
with fifteen in Europe and twenty-four in Japan.1 These are Terramycin
(oxytetracycline), Romet 30(orometopum sulfadimethoxine), Finquel
(tricaine methanesulfonate, or MS-222), formalin, and sulfamerazine. Finquel is an
anesthetic. Formalin is a parasiticide (a substance which kills disease-causing
agents known as parasites), and the remaining three are antibiotics.2 Sulfamerazine
is no longer manufactured because fish culturists purchased the cheaper
generic or nonfish versions of the drug.3 Each drug is approved only for
specific species of fish. They can be legally used only in those species,
at the listed dosages, and when certain disease conditions are present.

There are so few drugs because pharmaceutical companies are often hesitant
to invest millions in order to test a drug to be used in a relatively small
industry such as the aquaculture industry. The testing is necessary, however,
according to a 1991 National Academy of Sciences document in which it was
concluded that chemicals are not effectively controlled in aquaculture.4
Because of the lack of control, the NAS recommended that additional studies
be completed on contaminant risks, and that all imported seafood must meet
U.S. standards of safety. This matter is complicated by the fact that many
more drugs are approved for use in aquaculture in other countries, such
as Japan and those in the European Economic Community, which export a large
percent of aquacultural products consumed in the U.S. Other problems are
created as regulations and laws differ from country to country.

The Center for Veterinary Medicine (CVM) at the FDA is responsible for
reviewing and approving drugs for use in animals. Its primary enforcement
priority has been concerned with drug manufacturers and distributors. Its
secondary priority is concerned with medicated feed manufacturers. CVM,
through these regulatory strategies, aims to permit only approved drugs
to be in circulation and at the recommended dosage levels. CVM does not
do routine inspections for enforcement purposes. They do conduct "for cause"
inspections (in situations where the CVM has reason to believe that questionable
practices exist) and surveillances of drug investigators using drugs under
the investigational exemption status.5

Investigational New Animal Drug Exemptions. (INAD exemptions) permit the
testing of various types of drugs including antibiotics, general antimicrobials
(used to combat disease-causing agents), parasiticides (used to kill parasites),
anesthetics, and spawning aids (used to induce egg-laying). CVM reviews
the applications for this exemption and gives limited permission for its
use. According to Tom Bell of the FDA's Division of Therapeutic Drugs for
Animals, "INAD exemptions permit the otherwise illegal use of an unapproved
drug in studies designed to generate data required by CVM to approve the
drug."6

Previously, INAD exemption permits were occasionally issued for "compassionate
use." For example, the FDA recognized that at one time little or no data
were being generated on some compounds (such as erythromycin) under INADs
even though such data generation was required by law.7 Sometimes, the situation
is further complicated by the fact that if the FDA revises its INAD procedures,
the FDA may reverse its decision concerning a drug which once had INAD
status. Such is the case of the drug, malachite green. Upon re-evaluation,
the FDA concluded that insufficient evidence existed for its safe, experimental
use.8

According to the FDA's Tom Bell, "Before a drug can be approved for use
in fish ..., data must be submitted to CVM. The data must demonstrate that
the drug is safe and effective. These requisite data are produced under
both laboratory and productional settings. Fish tested under production
settings may be authorized by CVM, in some cases, to be either harvested
for human consumption or released into public waters. Harvest or release,
authorization will only be provided if sufficient information has been
provided to CVM from which to set a safe investigational withdrawal period
(minimum time from last drug exposure to harvesting, during which the drug
is depleted from edible tissues)."9 The data are intended to protect the
health of those consuming the previously exposed fish.

CVM has the authority to exercise discretion in deciding when to enforce
the law. So, for instance, the CVM "permits" the use of "low regulatory
priority drugs" such as salt and ice. These substances pose minor (if any)
safety concerns when used under specific conditions according to CVM. FDA
approval is not required for these drugs.10

This brief overview of drug regulation in aquaculture should give the seafood
consumer cause for concern. Many drugs used in farmed fish from other countries
have not been approved by the FDA. These fish are eaten in the United States
even though health risks associated with the drugs are not known. Furthermore,
fish which have been given experimental drugs in this country may be sold
on the market or released into public waters. The possible health and environmental
risks are not known. Considering the potentially negative health and environmental
effects, the reader may rightly question if drug use in aquaculture is
adequately controlled.

Effluent and Solid Waste

The EPA is primarily responsible for the regulation of effluent (discharged
waste water) and solid waste produced by aquaculture. Some aquacultural
facilities are required to apply for a National Pollution Discharge Elimination
Systems (NPDES) permit if their waste production is of a certain type and
quantity.

According to the regulation, "concentrated aquatic animal production facilities"
are point sources of pollutants (i.e., identifiable sources of pollution),
and as such they require NPDES permits for discharges into U.S. waters.11
These facilities include hatcheries, fish farms, or other facilities that
contain, grow, or hold aquatic animals. Facilities are divided into three
categories: (1) those which produce cold water species; (2) those which
produce warm water species; (3) any other facility deemed by the EPA Director
to be a significant contributor of pollution to U.S. waters.

There are exemptions to the first and second categories. Those facilities
producing cold water species such as trout or salmon are exempt if they:
1) produce less than approximately 20,000 pounds of animals per year, or
2) feed less than 5,000 pounds of feed during the calendar month of maximum
feeding. All other facilities which discharge at least thirty days per
year must have a NPDES permit.12

Secondly, those facilities producing warm water species such As catfish
or minnows are exempt if they discharge only during periods of excess runoff.
Also exempt in this category are facilities which produce less than 100,000
pounds of animals per year. All other facilities which discharge at least
thirty days per year must have a NPDES permit.13 Aquaculture practiced
in the tidal waters of Maine is exempt from the NPDES program.14

It is believed that these minimum standards set by the EPA will require
that most commercial cold water aquaculture facilities obtain NPDES permits.
Most warm water facilities, however, may be managed so as not to require
NPDES permits. Exemption from the NPDES permit program could be accomplished
by very large operations which time their discharges to periods of high
rainfall.15

There are also guidelines for uses of discharges into aquaculture products
(i.e., any aquatic plant or animal). These would apply to those aquaculturists
who recycle their waste water by using it as source water for the production
or maintenance of sea plants and animals.16

Despite the existence of many regulations, aquaculture will probably remain
relatively low on the priority list of the EPA as a point source or discharger
of pollution. The EPA is currently focusing its efforts on controlling
non-point sources (i.e., sources with no clearly identifiable point of
discharge). However, aquaculture facilities will most likely be included
in area-wide storm water management plans being developed on a state-by-state
basis using federal guidelines to control pollution from non-point sources. 17
Regulatory
agencies are primarily concerned with aquaculture facilities which use
open- and semi-closed culture systems (systems which have some direct connection
with open bodies of water). These systems, including raceways (long, rectangular
areas where fish are confined) and pens, more easily pollute surface and
ground water (water beneath the earth's surface that supplies wells and
springs) than indoor, recirculating systems. Indoor systems use less water
and integrate waste water treatment into their production process. Shellfish
nurseries and grow-out operations (where fish are brought up to market
size) are not considered as having a discharge; in fact they are often
viewed as water-improving activities. They are still subject to environmental
review for leases, siting, and harvest limitations.18

Solid wastes produced by aquaculture facilities are regulated separately.
Solid wastes include fish carcasses and the suspended solids removed from
liquid waste. When the solids are removed and become settled, sludge is
formed. Some states classify and regulate sludge as an industrial or municipal
waste. Other states consider it to be an agricultural waste because of
its value as a nutrient source. Fish carcasses are classified as either
an agricultural or as a non-hazardous solid waste.19

Sludge may be used as an agricultural crop fertilizer. Most states have
guidelines or regulations for the use of manures and other organic wastes
(including waste water). The sludge must be free of disease-causing agents,
heavy metals, and other contaminants. Composting of the carcasses for use
as a soil conditioner is becoming more popular; sometimes it is preferred
to land disposal. The carcasses may be recycled into fish meal (mealy substance
produced from fish or fish parts) or liquid.20

Regulations of aquacultural solid waste vary from state to state. For those
states which consider settled solids and fish carcasses to be animal manure,
crop residue, or farm by-products, aquacultural solid waste, like all agricultural
waste, would be exempt from solid waste regulation. Some states require
permits for the use of sludge as fertilizer. Small scale, non-commercial
operations may be exempt from state solid waste regulations and permit
requirements if the waste is used on-site following recommended application
guidelines.21

This brief summary of pollution control in aquaculture shows that regulation
is in place. However, it seems that there are ways by which individual
aquaculturists, both large and small, can avoid regulation. For example,
very large operations which discharge waste water at certain times of the
year are not required to obtain NPDES permits. Small-scale, non-commercial
facilities may also be exempt from regulation if they use their wastes
on-site. Considering the environmental effects of land and water pollution,
the reader may rightly question whether aquacultural effluent and solid
waste are adequately controlled.

Environmental Impacts of Aquaculture

We know that more than 50% of total world aquacultural production comes
from the coastal zone. This includes over 90% of all cultured mollusks,
crustaceans, and seaweeds.22 How does coastal aquaculture impact this environmental
zone?

Raising aquaculture species in concentrated areas causes overloading. This
means that there is more carbon and nitrogen present in the water from
fish waste products and fertilizer. The added elements result in an increase
in unwanted species and a reduction in the dissolved oxygen essential to
aquatic plants and animals.23 Environmental overloading occurs when the
environment is used so far beyond its capacity that the area becomes "spent."
What was once thriving habitat for native species is no longer so.24
Aquaculture
in developing countries has contributed to the destruction of mangrove
forests. In Brazil, for example, so much destruction has occurred that
the local climate has changed. It has changed to such a large degree that
some aquacultural operations have had to shut down.25 Without mangrove
habitat, the environment is also degraded in other ways. For instance,
without mangroves as a buffer system, there is decreased protection of
the shoreline against erosion and storm damage. There is also loss of nursery
ground for native fish and shrimp larvae.26

Coastal aquaculture can also impact native species when cultured species
intermingle with native species. For instance, cultured animals may escape
into the wild and breed with non-farmed animals. The high concentration
of cultured fish or shellfish may lead to outbreaks of disease which in
turn spread to the wild. Use of antibiotics in fish on farms where the
concentration of aquatic animals is high could lead to a weakening of the
antibiotics' effectiveness.27 There has already been a case of a species
of sea lice which had developed resistance to drugs used to treat it in
cultured stocks.28

In developing countries, aquaculture may also have an effect on the local
human population. Intensive aquaculture has adversely affected the livelihoods
of local shrimp farmers in Southeast Asia and in Latin America by diminishing
the farmers' ability to feed themselves and their communities. The locals'
extensive techniques (methods which use minimal technology) to produce
fish are far outpaced by the techniques of intensive (highly mechanized)
aquaculture. Furthermore, the locals' fish are bought by the intensive
aquaculturists to be used in shrimp feeds. The result for the locals is
often a decrease in self-sufficiency.29

Governments, international organizations, and aquaculture associations
are recognizing the need to address these and related environmental issues.
Several proposals have been suggested with the aim of reducing the environmental
impacts of aquaculture. The proposals include the formulation of coastal
aquacultural development and management plans. The plans include the establishment
of site selection criteria and the use of computer modeling.30 Other proposals
address the issues surrounding wastewater management. Proposed suggestions
include the following: site rotation, co-culture of species at different
levels of the food web, and reduction/rotation in the use of antimicrobials
used to kill disease-causing agents.31 These proposals aim to avoid the
problems associated with a monoculture (a crop where only one type of plant
or animal is grown), and those associated with repeated use of a certain
drug. Aquaculturists hope that these and related strategies will alleviate
the problems experienced in Western aquaculture.32 They also hope that
the strategies will prevent the reccurrence of the same problems in countries
where aquaculture is newer. The author will comment on these proposals
in the analysis at the end of the article.

The Future of Aquaculture

What will aquaculture look like in the 21st century? Here are a few ideas
based on strategies which aquaculture has developed as part of its waste
management systems.

Integrated farming is one method used by aquaculture in which nutrients
are recycled. It may take several forms, such as aquaculture-agriculture
systems. Rice-fish culture is included in this category. There are also
poultry-fish systems and soybean-fish culture. Italy boasts an integrated
lagoon management system known as vali-culture in which traditional fishery
practices, modern aquaculture, and recreational activities co-exist.33
Aquacultural
waste is an inexpensive source of minerals and organic matter and can be
used as fertilizer on cropland. It could also be used as a nutrient source
in the feeds of agricultural animals, such as using catfish processing
waste in poultry feeds.34 In the U.S. fish processing industry, wastes
are used to produce fertilizer for crops.35 Similarly, using manures from
other animals as fertilizer in aquaculture is another example of nutrient
recycling in an integrated aquaculture-agriculture system.36

There is growing interest in using treated human waste water in aquaculture.
Such a system is already operative in Asia.37 This interest is generated
by the rapid spread of urbanization. Using human excreta in aquaculture,
as in agriculture, will close the nutrient cycle, encompassing all members
of the food web. It has been predicted that the waste water treatment plants
of large cities will become centers of food production on a grand scale.38
Another
strategy used by aquaculture to recycle its waste products is through composting.
This process could be like that of the fisheries industry, where fisheries'
wastes (offal) are mixed with Sphagnum peat and composted. The production
of the offal-peat compost is an easy and economically feasible way to produce
a nutrient-rich fermentation medium for fungi.39 Research has also examined
the feasibility of using catfish pond sediment (pond mud) as a growing
medium for bell peppers. They found it to be quite satisfactory as compared
with field soil.40

There is, in fact, a growing connection between aquaculture and vegetable
hydroponics (the cultivation of plants without soil). This integrated system
relies on water recirculation. Therefore, it has great potential in regions
where water is scarce. The water from fish culture provides most of the
nutrients required by plants (a few are added to the water). Nutrient uptake
by plants improves water quality and can increase fish production.41 Because
chemical pesticides are very toxic to fish, biological methods to control
plant pests and diseases are currently under investigation. Such research
should be useful in traditional agricultural systems as well. Thus far,
experimental integrated systems have produced good yields.42

Author's Analysis

This article has presented the reader with a large volume of facts and
figures. How should the reader interpret all of it? Let's look more closely
at what the facts mean.

As in Part I of this article, the facts in Part II suggest that aquaculture,
from an environmental point of view, has both positive and negative aspects.
The information on drugs is the most controversial. The 1991 National Academy
of Sciences document which concludes that chemicals in aquaculture are
not effectively controlled leads the author to question the safety of aquacultural
products. The fact that fish which have received experimental drugs can
be sold for human consumption and released into public waters also presents
a safety concern.

These facts could have very serious consequences not only for fish eaters,
but for all of us. Negative consequences could result from the presence
in the environment of uncontrolled and experimental drugs. Residues from
these drugs could be released into the water and/or food web, eventually
making their way to unsuspecting consumers. This whole affair is worrisome.
We
should also point out that the large majority of fish eaten in the U.S.
is from foreign sources. As mentioned, the number of approved drugs for
aquaculture in other countries is much greater. However, we do not know
about the testing methods used to approve these drugs, or about the potential
risks associated with them. The investigative consumer, with enough persistence,
could probably find out from the fish supplier. However, this information
is not easily accessible. It is cause for concern.

With respect to effluent regulation, the author found it interesting to
discover that most small-scale aquaculture operations are exempt from EPA
regulation. It is also noteworthy that some large-scale operations could
make themselves exempt from regulation by timing their discharge to certain
periods of the year. These facts make the author wonder if effluent and
solid waste regulation in aquaculture even exists on a practical level.
Furthermore, the fact that shellfish nurseries and grow-out operations
are not considered as having a discharge, but, rather, are often viewed
as water-improving activities, supports the author's speculation.

When we consider on a global scale how the majority of aquaculture is conducted,
we see that aquaculture has a widespread and profound environmental impact.
As we reported in Part I of this article, members of the World Aquaculture
Society said at their 1996 Annual Conference that aquaculture must seek
to be "environmentally friendly." The author certainly agrees with this
imperative. Given the damage that aquaculture has created in Brazilian
mangrove forests, the surrounding environment, native fish species, and
local populations in the developing world, there is no doubt that people
in aquaculture need to look closely at how to mitigate the problem.

Granted, aquaculture farmers have begun to look at its practices from an
environmental point of view. As we mentioned, there are proposals to formulate
aquaculture development and management plans. We hope that these plans
will be successful so that everyone, including the environment, wins. However,
the author is wary of over-reliance on computer modeling as a solution
to serious problems. It can in no way perfectly account for all of the
variables which are present in natural systems. Again, we express hope
that aquaculture farmers will make prudent decisions based on these models,
relying principally on past experiences rather than predictions.

We applaud those in aquaculture for searching for ecological ways to re-use
its water and waste. Integra-ted farming and composting are environmentally
sound practices. So, too, is vegetable hydroponics. However, aquaculture
has far to go before it can be called "environmentally friendly."

Editor's note: Vegetarians do not eat meat, fish, or fowl. The purpose
of this article is not to condemn or condone the eating of fish, but to
educate readers about the various ramifications of aquaculture.

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